A device for a batch-type dispersion or a device for continuously dispersing has been used for dispersing solids in a liquid, such as a slurry or a mixture of a liquid and solids. However, by device for a batch-type dispersion a raw material may not evenly pass through a region for generating a shearing force for dispersing. Thus a part of the raw material may accumulate at a particular location in a vessel. That results in a longer time to obtain a uniformly dispersed material as a whole. By a device for continuously dispersing an insufficiently dispersed material may be obtained, since the raw material just one time passes through the region for generating shearing forces for dispersing.
To solve these problems, a system is known that comprises a tank for supplying a mixture to the device for continuously dispersing, a tank for receiving the mixture that has been dispersed by the device for continuously dispersing, and multiple paths for alternately changing the tank for supplying and the tank for receiving (see Japanese Patent Laid-open Publication No. 2009-51831). However, changing the paths for the tanks is troublesome. Thus a circulating-type dispersing system that includes a device for continuously dispersing was proposed. However, if the inlet and outlet of the device for continuously dispersing were just connected by piping, just a very small amount of the mixture could be processed. Therefore, a storage tank may be provided along the piping to increase the amount of the mixture to be processed (see Japanese Patent Laid-open Publication No. 2004-267991).
In that system some of the mixture may pass through the storage tank in a short time and some may stay there for a long time, before flowing out of the tank. Thus not all of the mixture may be processed by the device for continuously dispersing to the same degree. Thus a long time is required to obtain a uniformly processed mixture. That has been a problem.
The object of the present invention is to provide a system and a method for dispersing a large amount of a raw material uniformly and effectively by circulating it. By that system or method, a processed mixture can be obtained in a short time.